Method of and apparatus for precipitating copper from hot solutions



F. LAIST.

METHOD OF AND APPARATUS FOR PRECIPITATING COPPER FROM HOT SOLUTIONS,APPLICATION FILED SEPT. 8, 1919.

1,333,985. Patented Mar. 16,1920;

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METHOD OF AND APPARATUS FOR PRECIPITATING COPPER FROM HOT SOLUTIONS.

APPLICATION FILED SEPT. 8 1919. 1 ,333 ,985, Patented Mar. 16, 1920.

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F. LAIST.

' METHOD OF AND APPARATUS FOR PRECIPITATING COPPER FROM HOT SOLUTIONS.

APPLICATION FILED SEPT. 8, 1919.

1',333,985. Patented Mar. 16, 1920.

3 SHEETSSHEET 3.-

' Gum UNITED STATES PATENT OFFICE.

FREDERICK LAIsT, or ANACONDA, MONTANTA.

METHODflF AND "APPARATUS FOR TRECIPIIATING COPPER FROMI-IOT SOLUTIONS. I

Specification of Letters latent Patented D131. 16, 1920.

Application filedSeptember 8, 1919. Serial N0.-'322-;355.

To all whom it may concern:

Be it known that I, FREDERICK LAIs a citizen of the United States,residing at Anaconda,in the county of Deerlodge and State ofMontana,-have invented certain new and :useful Improvements in Methodsof and Apparatus "for Precip-itating Copper from Hot Solutions, of whichthe followingis a specification.

This invention relates tothe recovery of metals from solutions and moreparticularly to the precipitation ofcopper from hot solu tions. As anexampleof this class of inventions may be'mentioned the p-recipitationofcopper from hot sulfate solutions with sulfur dioxid.

According to the known practice, the roasted ore, matte or other copperbearing material is leached with an acid solution such, for instance, as'anacid solution of 1 copper sulfate, and the resultingcopper-enrichedsolution is impregnated with sulfur dioXid and heated to a considerabletemperature in a closed vessel, whereupon copper is precipitated. Theacid is thus freed and may be used for leaching further batches of ore.

The process is quite feasible, but itsipracticability is impaired by thefact that the heating of the copper solution in practice is an itemofconsiderable expense, since such solutions are generally rather diluteand seldom contain much more than 1% of copper. As ageneral rule'thehigher thetemperature to which the solution is heated, the greater willbe the percentage of copper precipitated. 1 a

The present invention comprises an improvement of the process asheretofore carried out and embodies certain novel features which makethe operation economical and highly practical.

According to the improvements, the heat remaining after the metal hasbeen precipitated from the solutionis used in a very effective manner topreheat the solution from which the copper is to be precipitated and isthus conserved to a veryconsiderable extent.

This and other features of the improvements will be more clearlyunderstood as the description proceeds reference being had to theaccompanying drawing, wherein;

Figure 1 illustrates diagrammatically ape paratus suitable for carryingout the invention;

Fig. Qisa view similar to Fig. 1 with certain modifications; and

Fig. 8 is a diagrammatic view of another modification. J V

Referring to Fig. -1, the numeral 1 indicates a closed precipitatingtank having a steam-supply pipe 2, extending some dis tance thereintoasshow'n. The steam-supplypipe 2 is provided with a suitable valve. 8.Near'the top of its conical bottom a, the tank 1 has a. liquoroutlet-pipe 5 equippedwith a valve 6, while at the bottom or apex of theconical part 4 the tank is provided with an outlet-pipe 7 for Withdrawalof precipitated metal. The pipe 7 has a suitable. valve 8. I

Near tank 1 is located a closed preheater 9, which may be of anysuitable form, but which for convenience is shown as similar in manyrespectsto the precipitating tank 1 A pipe 10 having a valve 11 suppliessteam to the upper part of the tank 9, anda pipe 12 having a valve 13connects the upper part of the precipitating tank 1 with the preheatingtank 9, the outlet of said pipe 12 in the preheater being preferablyfairly close to its bottom as shown. Such bottom 14, which mayconveniently be conical is provided with a draw-off pipe 15 having avalve 16.

Conveniently near-the preheating vessel 9 and elevated somewhat withrespect thereto is a receptacle 17 which may be termed a storage tank.This receptacle is closed and has anoutlet 17 leading to S0, compressor(not shown) for recovery of excess S0,. :It is connected at or near itsbottom with the preheating tank .9 by means of a conduit 18' providedwith a valve 19. A pipe QOhaving a valve 21 connects'the'top oftheprecipitating vessel 1 with the storage receptacle 17, the end 22 ofthe pipe 20 in the receptacle 1-7 being preferably rather close to thebottom thereof,

Below the levels of the tanks 1 and 9 and the storage receptacle 1-7,there is a heat-interchanger 23, preferably of the countercurrent typeillustrated. It may consist'ofya casing inclosing a bank of spaced tubes24 whose opposite ends open beyond the usual supporting tube-sheets intocompartments 25, 26 at 'theends of the casing. As is well under stood,in "the operation of a heat-interch'anger of this type one'ofthe fluidspasses from one. of the end compartments to *the other through thetubes, while the other fluid circulates freely in the chamber around thespaced tubes.

One of these end compartments, is shown as communicating with thestorage-tank 17 by means of a pipe 27, while the other end compartment26 is connected by a pipe 23 with a supply-tank 29, preferably elevatedsufiiciently to cause the solution therefrom to pass through theheat-interchanger 23 up into the storage-vessel 17. One end of thechamber around the tubes 24:, which chamber is indicated by the numeral30 in the drawings, is connected by pipe 31 with the bottom ofreceptacle 32 located beneath or beside the valved outlet 5 of theprecipitating vessel 1. The other end of the compartment 30 is shown incommunication with a pipe 33 whichleads to the top of a receptacle 31.The elevated supply-tank 29 is provided with a liquid-inlet pipe 35 andthe receptacle 3% has at or near its bottom a liquid-outlet pipe 36.

The precipitating operation as carried out in the apparatus described issubstantially as follows:

The precipitating tank 1 is filled approximately three-fourths full withthe copperbearing solution from which the metal is to be precipitated,such solution being preheated in a manner to be described to approximately 125 C. From this temperature, the heating to about 155 C. iscompleted by means of live steam taken from a boiler plant through thevalve 3. Prior to the treatment'with steam S0 is added in the usualmanner. The precipitation in tank 1 having been completed and a finaltemperature of about 155 C. having been attained, the valve 3 is closedand the valve 13 is opened, thus releasing the pressure on the surfaceof the liquid in tank 1, about 100 lbs. per inch, and causing the liquidto boil. The steam passes through pipe 12 into the solution contained intank 9. In about thirty minutes an equalization of pressure betweentanks 9 and 1 is accomplished and also an approximate equalization oftemperature results. What actually happens is that the pressure 'in tank1 falls from about 100 lbs. per square inch to about 30 lbs. and thepressure in tank 9 rises from zero to 30 lbs. At the same time thetemperature of the liquid in tank 1 falls from 155 C. to about 130 (3.while the temperature in tank 9 rises from about 100 C. to 125 C.

This having been accomplished the valve 13 is closed and the wave 21 isopened, permitting the steam, which naturally comes off, to flow intothe solution contained in tank 17 which has been raised within a fewdegrees of the boiling point by passage through the interchanger 23. Atthe same time, the acid liquor in tank 1 falls in temperature to theboiling point,

or about 100 C. and is allowed to flow into the hot solution storagetank 32 by opening the valve 6. From tank 32 the hot liquor flowsthrough pipe 31, through the jacket 30 surrounding the pipes 24:, in thedirection indicated by arrows, and then into the tank 34 whence it maybe pumped to the leaching plant (not shown) to be used as leachingsolution ona fresh charge of ore. The copper which has been precipitatedin tank 1 is drawn off by opening valve 8.

Thevalve 13 is now again opened and at the same time high pressure steamis admitted through valve 11 whereby the solution in tank 9 is forcedinto the tank 1 for treatmerit. Tank 9 is then recharged with boilingsolution from the storage tank 17.

The acid liquor, which is passed from the leaching vats to the tank29,passes through pipe 28 into the heat exchanger 23 and through thepipes 24 thereof and is thus heated by the hot solution flowing throughthe jacket 30, as previously described, from about 20 C. to 90 C. Theliquor passing from pipes 24: of the heat exchanger to the tank 17 thushas a tem perature of 90 and this temperature is raised, as previouslydescribed, by the steam coming from tank 1 to 100 C.

In place of a single preheating tank 9, a plurality of preheating tanksmay be employed in series. The pressure in tank 1 may be released downto say 60 lbs, in the first of these tanks, then down to, say 30 poundsin the second of these tanks, and then finally blown off into tank 17.

Fig. 2 shows an arrangement which is generally the same as that shown inFig. 1.

However, the tanks 1 and 9 are alternately j used as preheating andprecipitating tanks respectively. The liquor is alternately drawn fromthe tank 17 through valves 19 and 19 into tanks 1' and 9. After tank 1has been used as a precipitatingtank, the valve 13 is opened and thesteam allowed to pass into tank 9 to raise the temperature of the liquortherein to 125 C. as previously stated. When the pressure in the twotanks is equalized, valve 13 is closed and valve 21 opened to pass thesteam from tank 1 into tank 17 as previously described. The hot liquidis then drawn off from tank 1' into tank 32' by opening valve 6. Thetank 1 is then refilled by opening valve 19. The liquor in tank 9' isthen treated with steam by opening valve 3". After the treatment iscompleted, valve 13 is opened to permit the steam to pass into tank 1.After equalization in the tanks has been reached, valve 21" is opened tolet the steam pass into tank 17. The hot solution is now drawn offthrough valve 6" into tank 32".

The recovery of the heat is accomplished principally in ,tWo stages 2'.c. :first :by the utilization of :the liberated steam andthen by theutilization of the hot liquid. While a preheating tank, as described,may be conveniently resorted .to for raising .the temperature .of the.solution coming from the-tank l7vto a point in excess of thetemperature at atmospheric pressure, it may obviously be dispensed withand the appato the blowing off of steam directly into the solution. Itis, of course, understood that the heat energy of the steam may betransferred to the liquor through coils. In

' fact the character of the devices for transferring the heat energy ofthe steam and the hot metal-lean liquid to the metal-rich solution to bepreheated may be varied in various ways within the scope of the invention.

The improvement applies equally well to other solutions such as sulfateand chlorid solutions.

I claim:

1. The method of recovering copper which comprises leaching acopper-bearing material with an acid solution, impregnating a charge ofcopper-rich solution with sulfur dioxid, heating the impregnatedsolution to effect precipitation of copper and utilizing the heat energyof the steam remaining after precipitation for preheating another chargeof metal-rich solution.

2. The method of recovering copper which comprises leaching acopper-bearing material with an acid solution, impregnating a charge ofcopper-rich solution with sulfur dioXid, heating the impregnatedsolution to effect precipitation of copper and separately utilizing theheat energy of the steam and of the liquid remaining after precipitationfor preheating other charges of metal-rich solution.

3. The method of recovering copper from acid solutions, which comprisesimpregnating the solution with sulfur dioxid, injecting steam underpressure into the impregnated solution to precipitate copper, andpreheating the metal-rich solution with the residual steam of theprecipitating step.

4:. The method of recovering copper from acid solutions, which comprisesimpregnating the solution with sulfur dioxid, injecting steam underpressure into the impregnated solution to precipitate copper,

heating the metal-rich solution with it'llt) re sidual steam of theprecipitating step, and

preheatingsaidmetahrich solutioin byvmeans of the metal-lean solution.

5. The method ofrecovering copper from acid solutions, :which comprisesimpregnating the solution withsulfur dioxid, injecting steam underpressure into the impregnated solution :to precipitate copper, releasingthe pressure from the solution and utilizingthe steam given offduring-theme lease for heating a n'ietal-rich solution and utilizing themetal-lean I solution for heating the metal-rich solution.

6. In the process of recovering copper from hot acid solutions byimpregnating the solution with sulfur dioxid and injecting steam intothe impregnated solution, the method ofrecovering the heat from thetreated solution, which consists in separately utilizing the residualsteam and the residual metal-lean liquid present in the precipitatingchamber. after a precipitating operation to preheat charges ofmetal-rich solution to be subjected to treatment in the precipitatingchamber.

7 In the process of recovering copper from hot acid solutions byimpregnating the solution with sulfur dioxid and injecting steam intothe impregnated solution, the method of recovering the heat from thetreated solution, which consists in heat-- ing a new charge ofmetal-rich solution by means of the hot metal-lean solution remainingfrom one precipitating operation and then heating the charge by theresidual steam incident to a subsequent precipitating operation.

. 8. Apparatus for recovering copper'from hot solutions by impregnatingthe solution with sulfur dioXid and injecting steam into the impregnatedsolution, comprising a precipitating chamber, a feed connection forfeeding a metal-rich solution to the precipi tating chamber, said feedconnection includ ing a plurality of vessels, a controllable connectionbetween the top of the precipitating chamber and one of said vessels forbringing the steam remaining after precipitation into heat-exchangerelation with the solution in the feed-connection, and a controllabledrain connection leading from the lower portion of the precipitatingchamber to another of said vessels for bringing the hot liquid remainingafter precipitation into heat exchange relation with the solution in thefeed connection.

9. Apparatus for recovering copper from hot solutions by impregnatingthe solution with sulfur dioxid and injecting steam into the impregnatedsolution, comprising a precipitating chamber.a feed connection forfeeding a metal-rich solution to the precipitating chamber, said feedconnection including a plurallty of vessels in series, a con trollablcconnection leading from the top of the precipitating chamber into each01 said vessels and terminating near the bottom thereof and means forcontrolling the feed section between the two vessels.

10. Apparatus for recovering copper from hot solutions by impregnatingthe solution with sulfur clioxicl, and injecting steam into theimpregnated solution, comprising a precipitating chamber, a feedconnection for feeding a metal-rich solution to the precipitatingchamber, said feed connection including a plurality of vessels inseries, the first of the series being a heat exchanger, a controllableconnection leading from the top of the precipitating chamber into eachof the other vessels and terminating near the bottom thereof, means forcontrolling the feed section between the said last mentloned vessels,and a controllable connection between the bottom of the precipitatingchamber and the heat exchanger.

in testimony whereof I affix my signature in presence of tWo Witnesses.

FREDERICK LAIST.

lVitnesses BAYARD S. lVIORROW, SELDEN S. RODGERS.

